DESCRIPTION: Pulmonary arterial hypertension (PAH) affects thousands of Americans of all ages, with disproportionate disease in young women. Despite recent progress PAH takes the lives of a third of all patients within 3 years. Our preliminary studies indicate that a complicate interplay of events, including altered estrogen metabolism and insulin resistance, drive energy production defects, abnormal intracellular trafficking, and cytoskeletal defects which characterize and promote the cardiovascular dysfunction characteristic of PAH. The central theme of our program is to intervene against downstream mechanisms which we have shown to be important in PAH pathogenesis and for which translational therapies are currently available. Our hypothesis is that optimal treatment of the dysfunctional metabolic pathways which underlie PAH will improve pulmonary vascular function and consequences of the disease. Our goal is to develop highly effective therapy, which will also have benefit for pulmonary hypertension which complicates many common heart and lung diseases. In Project 1 we will validate 2-methoxyestradiol as a treatment for PAH using multiple approaches, including epidemiology and functional studies of estrogen metabolite balance on lung vascular and cardiac function. This will confirm and extend studies demonstrating that diversion of estrogen metabolism away from 2- hydoxylation and towards 16?-hydroxylation contributes to excess PAH in females. In Project 2, we will test metformin as a treatment for PAH, extending our findings of insulin resistance and metabolic syndrome in PAH, using multiple approaches including metabolic phenotyping, epidemiology, and patient interventions. In project 3, we will pursue ACE2 as a treatment for PAH, extending our previous finding that ACE2 is an effective intervention in murine BMPR2-related PAH. In combination with other studies within the Vanderbilt PAH program, we plan for each of these treatments to be ready for clinical trials during a second five year period. Each of these treatments is targeted at recently identified basic pathogenetic mechanisms of disease. This novel program builds directly on recent discoveries of PAH mechanisms to develop therapeutics targeted to interdict those biologic pathways.